All of the "Move Semantics" exercises involve manipulating the code at the following playpen link:
Remove the mut from the binding of vec1 on the line marked (*) in the Move Semantics Playpen. Why does the code stop compiling?
(Put the mut back afterward.)
Try to change the first println! call, on the line marked (**) in the Move Semantics Playpen, so that it reports the length of vec0 after fill_vec returns.
(One quick way to do this is to just replace vec1 with vec0 in the println! call.)
Why doesn't the code compile successfully anymore?
(You can skip these exercises and come back to them after you have done the other core exercises, if you like.)
On the line marked (***) in the Move Semantics Playpen, the whole line (that is, the rebinding of vec to mut vec) can be removed if we just add the keyword mut to another spot in fn fill_vec. Figure out how to remove the line marked (**).
(Hint: in general, the use of mut is not attached to let -- rather, such a mut is attached to bindings)
Refactor the code in the Move Semantics Playpen so that instead of creating the vector in fn main, we instead create it within fn fill_vec, and transfer the freshly created vector from fill_vec to its caller. Note this will require revising the function signature for fill_vec.